As the above-mentioned volumetric flowmeter, there has been known, for example, a volumetric flowmeter proposed by the applicant of the present application as described below as Patent Literature 1. Now, a configuration and structure of a related-art volumetric flowmeter are described with reference to the drawings.
In FIG. 7, a volumetric flowmeter 101 includes a main body 102 and a calculation unit 103 mounted on the main body 102. As illustrated in FIG. 8, the volumetric flowmeter 101 is a flowmeter (instrumentation device), which is mounted in a midway part of a pipe 104, and can meter a fluid to be measured flowing through an inside of the pipe 104 and perform calculation regarding a flow rate to display the calculation result in the calculation unit 103. The above-mentioned display is performed by a display unit 105 described later.
In FIG. 8, a strainer 107 is arranged between the pipe 104 on an upstream side and an upstream-side flange 106 of the main body 102 . There is illustrated a bypass pipe 108 in FIG. 8. Further, there are illustrated valves 109. The bypass pipe 108 is arranged as a portion to be used for an overhaul of the volumetric flowmeter 101.
In FIG. 7 and FIG. 9, the main body 102 includes: a front lid portion 113 on which a mounting base 112 of the calculation unit 103 is mounted; a metering chamber forming portion 115 including a metering chamber 114; two rotors 117 and 118, which are accommodated in the metering chamber 114, and are rotated by rotor shafts 116; and the upstream-side flange 106 and a downstream-side flange 110 contiguous to the metering chamber forming portion 115. The front lid portion 113 is formed into a member for covering the metering chamber 114 under a state in which the rotors 117 and 118 are accommodated in a rotatable manner in the metering chamber 114. The front lid portion 113 is fixed to the metering chamber forming portion 115 with screws 119.
The rotor 117 includes two magnets 122, that is, an S-pole magnet and an N-pole magnet. The two magnets 122 are arranged at a distance as illustrated in the figure. The two magnets 122 are detected by a detection unit accommodated in a recessed portion 123 of the front lid portion 113, that is, a flow rate detection unit (not shown) of the calculation unit 103.
There is illustrated a pulse transmitter 127. The pulse transmitter 127 is connected to, for example, an F/I converter (not shown) and an integrator (not shown) through an output cable 128. The F/I converter and the integrator are provided in, for example, a remote management chamber.
A display main body unit 124 includes a unit case 129, a substrate having the display unit 105 mounted thereon, and a battery (not shown) for supplying electric power to the substrate. The substrate is accommodated in the unit case 129, and is fixed thereto with screws. The battery is also accommodated in the unit case 129. A cover 125 includes a transparent viewing portion 130 facing the display unit 105, and switches 131 and 132 for operation.